Sonic noise alert patterns, (SNAP's), are a series of depressions cut into the surface of asphalt roads. They are placed in lines along borders which generally are not crossed by a vehicle at a cruising speed without the specific guidance of the operator of the vehicle. The principal location of these series are along the edges of the road between the normal driving lane and the shoulder of the road. The shoulder is commonly comprised of loose earth with a vegetation cover such as grass. Scattered along this area are various objects which are hazardous if contact is made with a vehicle travelling at a normal cruising speed. The primary purpose of these SNAP's is to alert drivers that they have left the normal driving lane and therefore that a dangerous condition is being approached. The rumbling of the vehicle as they cross these depressions cause vibration to the vehicle and results in a audible sound being generated by the vehicle. Transportation management personnel have found SNAP's to be extremely effective in reducing vehicular accidents on roads with a proper installation of SNAP type depressions.
A common method of installing SNAP type depressions is with a machine equipped with a single rotary milling head. The machine is paused, a single plunge cut is made, then the machine is advanced, paused, and the procedure is repeated. This method results in the number of cutting procedures required to install the SNAP's being equal to the number of depressions in the series.
A second method has a multiheaded cutting tool, with the rotary cutting heads in a row, making a single plunge cut to form a first group of depressions. Then the multiheaded cutting tool is advanced by a distance to allow a plunge cut to form a second group of depressions between each of the adjacent prior cuts and one cut beyond the prior group. Then the machine is advance beyond the group formed by the combination of these two sets, and the procedure starts anew and is performed in repetition to form the desired series. This method requires the use of a plurality of cutting drums equal to the number of depressions within each of the two groups of depressions. The group formed by the two cutting actions, due to the precision placement of the tool, results in an overall spacing that tends to be less accurate than desired. The machine, due to the plurality of cutting heads, is significantly more expensive than a single headed cutting machine.
Fore the foregoing reasons, there is a need for a simple single headed cutting tool capable of installing a plurality of depressions in a single cutting procedure.